In the past, housings for rotating electric machinery had utilized a frame and shaft bearing bracket combination to provide an open drip-proof enclosure. In such prior art structures, the frame and shaft bearing brackets were specially designed and suitable only for such open drip-proof applications. A new frame member and new bearing brackets were required when a totally enclosed structure was required. This necessitated a separate inventory of such machinery enclosure parts and resulted in additional cost and complexity for rotating electric machinery manufacturers.
In addition, such open drip-proof structures, particularly in the bearing brackets, had relatively small inlet air apertures, reducing cooling effectiveness. Finally, such prior art inlet apertures conventionally were located below the shaft centerline, often near the base of such machinery when it was mounted for horizontal shaft operation, thus increasing the possibility of contamination of such machinery by dirt or other foreign material resting on the surface on which such machinery was mounted.
The present invention overcomes these disadvantages of the prior art open drip-proof structures by providing for utilization of totally-enclosed type bearing brackets in a new open drip-proof construction which provides for an air inlet aperture permitting the intake of air above the shaft center line. This new construction greatly increases the effective cooling, and reduces the probability of contamination by dirt or other debris resting on the machinery mounting surface in horizontal shaft applications, and reduces the number of parts needed for inventory by allowing the use of totally enclosed bearing brackets in open drip-proof applications. The present invention is useful for any electric machinery which uses cooling air, e.g., motors, generators or electromagnetic clutches or brakes.